The present invention relates to a multicylinder internal combustion engine, and more particularly to a multicylinder internal combustion engine with a rotation sensor and distributor.
Recent years have seen the rapid development of electronic controls of automotive engines. Where an engine having a fuel injection device is controlled by an electronic controller, the electronic controller is required to be supplied with various items of information related to engine rotation such as the top-dead-center positions of engine pistons and the identification of cylinders into which fuel is to be injected, in order to control the amount of fuel to be injected, the timing of fuel injection, and the ignition timing with high accuracy. These information signals have heretofore been generated by an electromagnetic sensor mounted on a crankshaft or a shaft rotatable in timed relation to the crankshaft.
The engine has a distributor for distributing high-voltage surges respectively to spark plugs. The distributor is generally coupled directly to the crankshaft or via a gear to the crankshaft. The distributor is apt to malfunction due to mechanical hysteresis or wear, and hence may cause a problem in high accurate engine control.
In those engines which have a plurality of camshafts, such as a V-shaped engine and a DOHC engine, the camshafts are driven by a crankshaft through a single endless belt and pulleys mounted on the camshafts and the crankshaft. The endless belt on the pulleys on the camshafts is subjected to different tensions, i.e., larger and smaller tensions, which act on the respective camshafts as a result of the direction in which the crankshaft is rotated.
The difference between these varying tensions on the camshaft pulleys has no appreciable effect on the mechanism operation of intake and exhaust valves. However, where the belt stretch between the camshafts is relatively large as in a V-shaped engine, the difference between the varying tensions on the camshafts adversely affects the response of an electric signal generated by a sensor. Therefore, control accuracy may not be good enough if the engine control sensor or distributor is positioned in a certain location.
In the event that the rotation sensor and distributor are mounted on one end of one rotatable shaft, the engine tends to be elongated or to be in physical interference with other accessories.
Furthermore, the electromagnetic rotation sensor is normally coupled to an end of the crankshaft or assembled in the distributor inasmuch as the sensor essentially serves to detect the rotation of the crankshaft. This arrangement has however led to an increased engine length or a complex structure, resulting in a high cost of manufacture.
The inventors have found that in a V-shaped engine having a pair of cylinder banks inclined in a V configuration, the end faces of cylinder heads in the direction of cylinder arrays are offset from each other since connecting rods extend from a crankshaft into the cylinder banks, which provides additional space at one end of a cylinder head for the rotation sensing components without lengthening the engine.